SYNTHESIS AND CHARACTERIZATION OF SOLID PHASE GRAFT COPOLYMERIZATION BY STYRENE AND MALEIC ANHYDRIDE ONTO POLYPROPYLENE

采用过氧化苯甲酰作引发剂,二甲苯作界面活性剂,通过固相接枝马来酸酐和苯乙烯对等规聚丙烯进行改性．研究了引发剂浓度、单体浓度和单体比例对接枝率和接枝效率的影响．利用傅立叶变换红外光谱和裂解气象色谱－质谱对接枝共聚物进行了表征．结果表明,采用双单体（马来酸酐和苯乙烯）接枝聚丙烯得到的接枝共聚物其接枝率要明显高于聚丙烯单接马来酸酐．     

Antigen-dependent increase in cytosolic free calcium in specific human T-lymphocyte clones

Calcium has been implicated as an intracellular messenger in the cellular response to various external stimuli. Exposure of lymphocytes to various mitogens and lectins results in rapid transmembrane calcium fluxes and increased cytoplasmic calcium concentrations ([Ca2+]i). It is not clear, however, whether the mechanisms by which these non-physiological stimuli activate cells are related to those involved in antigen-specific activation. We have now used antigen-specific T-cell clones to study changes in [Ca2+]i associated with specific activation and show here that these cells respond specifically in the presence of antigen and antigen-presenting cells (APC) with increased [Ca2+]i and that this increased [Ca2+]i shows the same genetic restrictions as are seen in the proliferation assay. The kinetics of the [Ca2+]i response to antigen indicate that antigen undergoes a time-dependent processing step as a prerequisite for recognition by T cells, as has been shown for T-cell proliferative responses, but that the [Ca2+]i response to processed antigen is extremely rapid. The close correlation between changes in [Ca2+]i and cell activation resulting in proliferation suggests that Ca2+ may act as an intracellular messenger in antigen-specific responses.     

Acetylsalicylic acid-induced morphological changes in the ductus arteriosus of the chick embryo

Summary The effect of acetylsalicyclic acid upon the ducti arteriosi of the embryonic chick was studied. A spectrum of gross malformations and histological findings associated with premature closure of the right ductus arteriosus is presented.This study was supported by grant No. HL18050, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland. The authors wish to extend their appreciation to John M. Opitz, University of Wisconsin Department of Genetics, for his generous support. This report was presented in part at the Fiftieth Scientific Sessions, American Heart Association Meetings, Miami, Florida, November 1977.     

含氧燃料添加剂对柴油机微粒排放的影响

研究了含氧燃料添加剂对柴油机微粒排放的影响。利用静电微粒筛选器和动力微粒筛选器对燃烧不同比例氧化燃料添加剂的柴油机废气中的微粒分布进行了测量。同时，还分别利用红外气体分析仪、火焰离子探测器和化学发光分析仪对相同样气中的一氧化碳、碳氢和氮氧化物的排放特性也进行了测量。研究表明含氧燃料添加剂对柴油机微粒的分布有影响，它能显著地降低碳烟的排放，而对一氧化碳、碳氢和氮氧化物的排放影响不大。     

Detecting deterministic dynamics of cardiac rhythm

Under the acceptable hypothesis that cardiac rhythm is an approximately deterministic process with a small scale noise component, an available way is provided to construct a model that can reflect its prominent dynamics of the deterministic component. When applied to the analysis of 19 heart rate data sets, three main findings are stated. The obtained model can reflect prominent dynamics of the deterministic component of cardiac rhythm; Cardiac chaos is stated in a reliable way; Dynamical noise plays an important role to the generation of complex cardiac rhythm.     

Acetylsalicylic acid-induced morphological changes in the ductus arteriosus of the chick embryo.

The effect of acetylsalicyclic acid upon the ducti arteriosi of the embryonic chick was studied. A spectrum of gross malformations and histological findings associated with premature closure of the right ductus arteriosus is presented.     

米曲霉α-淀粉酶的产生及其性质的初步研究

由中山大学生物学系微生物学教研室自行选育得到的一株米曲霉,在以家禽羽粉(或猪血粉)为主要氮源的培养基上,能向胞外分泌α-淀粉酶.产酶能力的最高纪录为每毫升发酵液含6×10~4蓝值下降单位(或300碘反应消失单位).本文报告该菌株的产酶模式和该酶的一些基本催化性质.     

Lactacystin-induced apoptosis of cultured mouse cortical neurons is associated with accumulation of PTEN in the detergent-resistant membrane fraction

The tumor suppressor function of PTEN is attributed to its phospholipid phosphatase activity that dephosphorylates the plasma membrane phosphatidylinositol-(3,4,5)-triphosphate [PtdIns(3,4,5)P₃]. Implicit in this notion is that PTEN needs to be targeted to the plasma membrane to dephosphorylate PtdIns(3,4,5)P₃. However, the recruitment of PTEN to the plasma membrane is not fully understood. Here, we demonstrate PTEN accumulation in the detergent-insoluble fraction of neuronal cells in response to treatment by the proteasome inhibitor lactacystin. First, lactacystin induces apoptosis and the activation of caspase-3 in cultured cortical neurons. Second, PTEN undergoes proteolysis to form a truncated 50-kDa form that lacks parts of its C-terminal tail. Third, the truncated PTEN is stably associated with the detergent-insoluble fraction in which the plasma membrane marker protein flotillin-1 resides. Taken together, our results suggest that truncation and accumulation of PTEN to the detergent-insoluble membrane fraction are two events associated with the apoptotic signals of the proteasome inhibitor in cortical neurons.Received 24 March 2004; received after revision 26 May 2004; accepted 5 June 2004